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Investments - Additional Information (Detail) - USD ($)
6 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Schedule of Investments [Line Items]    
Available-for-sale debt securities, allowance for credit losses $ 0 $ 0
Purchase an available-for-sale debt securities with credit deterioration $ 0  
Investment [Member] | Issuer Concentration [Member] | Market Value of Total Investment Portfolio [Member]    
Schedule of Investments [Line Items]    
Investment concentration risk percentage 5.00%